The present invention relates to a suspension-level microactuator having an improved stroke length. More particularly, it relates to a microactuator located in-plane along a suspension in a disc drive system and having an electroactive element to selectively move a transducing head radially with respect to a rotatable disc.
Disc drive systems include disc drive suspensions for supporting transducing heads over information tracks of a rotatable disc. Typically, suspensions include a load beam having a mounting region on a proximal end, a flexure on a distal end, a relatively rigid region adjacent to the flexure, and a spring region between the mounting region and the rigid region. An air bearing slider which supports the transducing head is mounted to the flexure. The mounting region is typically attached to a base plate for mounting the load beam to an actuator arm. A motor which is controlled by a servo control system rotates the actuator arm to position the transducing head over the desired information tracks on the disc. This type of suspension is used with both magnetic and non-magnetic discs.
In an effort to increase the storage capacity of hard disc drives, the density of concentric data tracks on magnetic discs continues to increase (i.e., the size of data tracks and radial spacing between the data tracks continues to decrease). Therefore, a corresponding improvement in the accuracy of the positioning system that locates the transducing head over a particular track is needed. Conventionally, the positioning system uses a single-stage, closed-loop feedback system in which a large-scale actuation motor, such as a voice coil motor, acts in response to a control signal based on position error information from the read head to radially position a head on a slider at the end of the actuator arm. This system is approaching the limit of its ability to follow the ever-narrower tracks and to reject the vibrations and disturbances present in the drive environment. This inability to follow the narrow tracks is due in large part to the significant length of structure between the voice coil motor and the head and the in-loop resonances which result from the structure. Thus, a high resolution head positioning mechanism is needed to accommodate the more densely spaced tracks.
One promising design for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional low resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. These designs, however, have shortcomings that limited the effectiveness of the microactuator. Many designs increased the complexity of designing and assembling the existing components of the disc drive, while other designs were unable to achieve the force and bandwidth necessary to accommodate rapid track access. Therefore, the prior designs did not present ideal microactuator solutions.
The positioning of a transducing head through dual-stage actuation using electroactive elements has been disclosed in prior patent applications. One such application is U.S. patent application Ser. No. 09/311,086, filed May 13, 1999 by Budde et al. entitled xe2x80x9cPIEZOELECTRIC MICROACTUATOR SUSPENSION ASSEMBLY WITH IMPROVED STROKE LENGTH,xe2x80x9d which is assigned to Seagate Technology, Inc., the assignee of the present invention, and is hereby incorporated by reference. Another such application is U.S. patent application Ser. No. 09/553,220, filed on even date herewith by Boutaghou, Crane, Mangold, and Walter entitled xe2x80x9cBENDING MICROACTUATOR HAVING A TWO-PIECE SUSPENSION DESIGN,xe2x80x9d which is assigned to Seagate Technology, Inc., the assignee of the present invention, and is hereby incorporated by reference. There remains a need in the art, however, for an electroactive element microactuator design that provides efficient high resolution head positioning in a dual-stage actuation system, allows for a greater range of motion than current designs, has reduced in-loop resonances, and is easy to manufacture and install.
The present invention is a microactuator for selectively altering a position of a transducing head carried by a slider, in a disc drive system, with respect to a track of a rotatable disc having a plurality of concentric tracks. The disk drive system includes an actuator arm. The microactuator includes a load beam attached to a distal end of the actuator arm. The load beam has a first section and a second section. A flexure is connected to the second section of the load beams for supporting the slider carrying the transducing head. A hinge is attached between the first section and the second section, the hinge being flexible to permit movement of the second section with respect to the first section in the general plane of the load beam. A bending motor is connected between the first section and the second section of the load beam along a longitudinal centerline of the load beam. The bending motor is deformable in response to a control signal.